1. Field of the Invention
The invention relates to integrated circuit nonvolatile memory. In particular, the invention relates to programmable resistive nonvolatile memory, such as phase change memory.
2. Description of Related Art
Nonvolatile memory stores data without requiring a continuous supply of power. Programmable resistive memory such as phase change memory is an example of nonvolatile memory. A high current reset electrical pulse melts and quenches the programmable resistive element into an amorphous state, raising the resistance of the programmable resistive element. A low current set electrical pulse crystallizes and lowers the resistance of the programmable resistive element.
Although the reset electrical pulse requires a high current, the structure of a programmable resistive RAM cell is a factor limiting the amount of current flowing through the programmable resistive element of the cell. The physical positioning of the contacts on either end of the programmable resistive element, requires the high current reset pulse to flow through an end of the programmable resistive element with a relatively small physical cross-section. Accordingly, it would be desirable if the high current reset pulse could flow through a larger physical area to reach the programmable resistive RAM cell.